US6756315B1ExpiredUtility

Method of forming contact openings

56
Assignee: CYPRESS SEMICONDUCTOR CORPPriority: Sep 29, 2000Filed: Sep 29, 2000Granted: Jun 29, 2004
Est. expirySep 29, 2020(expired)· nominal 20-yr term from priority
Inventors:Hanna BamnolkerPrashant B. PhatakUsha RaghuramSam Geha
H10W 20/081H10P 70/234
56
PatentIndex Score
7
Cited by
20
References
25
Claims

Abstract

The present invention provides a method of forming, in semiconductor substrates, contact openings having low contact resistance. The method involves, in particular, the introduction of a “soft etch” cleaning step that is used to clean the bottom of the contact openings. The “soft etch” cleaning step uses fluorocarbon chemistry. It is shown that the resulting resistance of the contact openings is reduced.

Claims

exact text as granted — not AI-modified
What is claimed is:  
     
       1. A method of forming a contact opening, comprising the sequential steps of: 
       etching an opening in an oxide layer over a substrate;  
       cleaning the opening in the oxide layer and the substrate with a wet cleaning process; and  
       exposing the opening to a substantially oxygen free plasma comprising, as the sole chemical etchant component thereof, one or more fluorocarbons each of which consists of fluorine and carbon atoms, to remove at least some contaminant from the bottom of the opening.  
     
     
       2. The method of  claim 1 , wherein the substrate comprises silicon. 
     
     
       3. The method of  claim 1 , wherein the fluorocarbon etchant comprises a compound of the formula C x F y , where x is from 1 to 4, y is 2x−2, 2x or 2x+2 and y is greater than or equal to 4. 
     
     
       4. The method of  claim 3 , wherein the fluorocarbon etchant comprises C 2 F 6 . 
     
     
       5. The method of  claim 1 , wherein the exposing step is carried out at a pressure of from about 100 mTorr to about 1500 mTorr. 
     
     
       6. The method of  claim 1 , wherein the opening has a diameter that is less than or equal to about 0.15 micrometers. 
     
     
       7. The method of  claim 1 , wherein the opening has an aspect ratio that is greater than or equal to about 4. 
     
     
       8. The method of  claim 1 , further comprising, after said exposing step, depositing a conductive material into said contact opening. 
     
     
       9. The method of  claim 1 , further comprising, after said exposing step, cleaning said opening and said substrate by sputter etching. 
     
     
       10. The method of  claim 1 , wherein one or more gates are disposed on the substrate, each of the one or more gates encapsulated by spacers and a cap, and wherein the step of etching an opening in an oxide layer exposes a spacer or a cap of at least one of the one or more gates. 
     
     
       11. The method of  claim 1 , wherein said plasma in said exposing step comprises a capacitively coupled plasma. 
     
     
       12. A method of forming a contact, comprising the sequential steps of: 
       etching an opening in an oxide layer, the oxide layer being in contact with a substrate of a device;  
       cleaning the opening in the oxide layer and the substrate of the device with at least one of a wet cleaning and a stripping composition;  
       exposing the opening to a substantially oxygen free plasma comprising, as the sole chemical etchant component thereof, one or more fluorocarbons each of which consists of fluorine and carbon atoms, to remove at least some contaminants from a bottom of the opening; and  
       depositing a conductive material into said opening, thus forming a contact.  
     
     
       13. The method of  claim 12 , wherein the substrate comprises silicon. 
     
     
       14. The method of  claim 13 , wherein the opening has a diameter that is less than or equal to about 0.15 micrometers. 
     
     
       15. The method of  claim 13 , wherein the opening has an aspect ratio that is greater than or equal to about 4. 
     
     
       16. The method of  claim 12 , further comprising sputter etching said substrate exposed in the opening after said exposing step. 
     
     
       17. The method of  claim 12 , wherein the plasma comprises an inductive coupled plasma. 
     
     
       18. The method of  claim 12 , wherein the plasma comprises a capacitive coupled plasma. 
     
     
       19. The method of  claim 12 , wherein one or more gates are disposed on the substrate, each of the one or more gates encapsulated by spacers and a cap, and wherein the step of etching an opening in an oxide layer exposes a spacer or a cap of at least one of the one or more gates. 
     
     
       20. A method of forming a contact opening, comprising the sequential steps of: 
       etching an opening in an oxide layer over a substrate;  
       cleaning the opening in the oxide layer and the substrate with at least one of a wet cleaning and a stripping composition; and  
       exposing the entire opening created in the etching step to a plasma comprising a fluorocarbon etchant and a carrier gas, wherein the plasma is substantially free of oxygen and hydrogen containing species, to remove at least some contaminants from a bottom of the opening to form the contact opening.  
     
     
       21. The method of  claim 20 , wherein the opening has a diameter that is less than or equal to about 0.15 micrometers. 
     
     
       22. The method of  claim 20 , wherein the opening has an aspect ratio that is greater than or equal to about 4. 
     
     
       23. A method of forming a contact opening comprising the steps of: 
       etching an opening in an oxide layer over a substrate, the opening having a width no greater than about 0.15 micrometers;  
       cleaning the opening with at least one of a wet cleaning and a stripping composition; and  
       exposing the opening to a substantially oxygen free plasma comprising a carrier gas and, as the sole chemical etchant component thereof, one or more fluorocarbons each of which consists of fluorine and carbon atoms.  
     
     
       24. A method of forming a contact opening comprising the steps of: 
       etching an opening in an oxide layer over a substrate, the opening having an aspect ratio of at least about 4;  
       cleaning the opening with at least one of a wet cleaning and a stripping composition; and  
       exposing the opening to a substantially oxygen free plasma comprising a carrier gas and, as the sole chemical etchant component thereof, one or more fluorocarbons each of which consists of fluorine and carbon atoms, to remove at least some contaminants from a bottom of the opening.  
     
     
       25. A method of forming a contact opening comprising the sequential steps of: 
       etching an opening in an oxide layer formed over a substrate to expose a bottom surface;  
       cleaning the bottom surface using at least one of a wet cleaning process and a dry cleaning process; and  
       exposing the opening to a plasma to remove at least some contaminants from the bottom surface, the plasma being substantially free from oxygen and hydrogen, the plasma comprising a carrier gas and one or more fluorocarbons, each of which consists of fluorine and carbon atoms;  
       wherein the opening has an aspect ratio of at least about 4 and a width no greater than about 0.15 micrometers.

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